An integrated circuit (IC) needs to be tested before it can be reliably used. For example, test data, also refer to as test patterns, may be loaded onto an integrated circuit and be processed by the integrated circuit to generate transformed patterns which may then be compared against expected patterns to determine whether the integrated circuit has processed the test patterns correctly. The increasing complexity of integrated circuits has led to ever larger test patterns, making efficient testing of the integrated circuit difficult.
International publication number WO 2005/006189 A1 describes an automatic self-test of an integrated circuit component in which input-output (I/O) circuitry tests itself, independent of a core logic of the component. In the test mode, an output portion of an I/O buffer is connected back to an input portion of the I/O buffer, thus providing a loop-back for driving data back through the input portion of the I/O buffer. The I/O buffer can thus be tested independently of any other components that may be connected to the I/O buffer in a normal operating mode. The test does, however, not cover the core logic of the IC component.